There were problems importing the following widgets: OWDiscretize: the sip module implements API v8.0 to v8.1 but the PyQt4.Qwt5.Qwt module requires API v5.0 OWCalibrationPlot: name 'QwtPlotCurve' is not defined OWLiftCurve: name 'QwtPlotCurve' is not defined OWROC: name 'QwtPlotCurve' is not defined OWMDS: name 'QwtPlotCurve' is not defined OWNetExplorer: name 'QwtPlotCurve' is not defined OWNetworkFromDistances: name 'QwtPlotCurve' is not defined OWCorrAnalysis: name 'QwtPlotCurve' is not defined OWDistributions: name 'QwtPlotCurve' is not defined OWLinProj: name 'QwtPlotCurve' is not defined OWParallelCoordinates: name 'QwtPlotCurve' is not defined OWPolyviz: name 'QwtPlotCurve' is not defined OWRadviz: name 'QwtPlotCurve' is not defined OWScatterPlot: name 'QwtPlotCurve' is not defined OWSieveMultigram: name 'QwtPlotCurve' is not defined OWSurveyPlot: name 'QwtPlotCurve' is not definedThe following widgets could not be imported and will not be available: OWLiftCurve, OWRadviz, OWCalibrationPlot, OWSurveyPlot, OWScatterPlot, OWParallelCoordinates, OWNetworkFromDistances, OWCorrAnalysis, OWNetExplorer, OWMDS, OWPolyviz, OWDistributions, OWSieveMultigram, OWROC, OWDiscretize, OWLinProj.

Do you by any chance also have Python 2.5 and PyQwt for it installed. If so, can you try to temporarily rename the Pyhton25 directory (by default C:\Python25) to something else (e.g. C:\Python25-tmp) and then run orange canvas for Python 2.6.

Try this: uninstall PyQwt5 and PyQy from the ControlPanel / Add Remove Programs. Then check if the directory C:\Python26\Lib\site-packages\PyQt4 still exists. If so manually delete the directory.Then download the orange with required libraries installer and run it.